This application is based on and incorporates herein by reference Japanese Patent Applications No. 2002-196055 filed on Jul. 4, 2002, and No. 2003-162323 filed on Jun. 6, 2003.
The present invention relates to a control device for a hybrid-driven auxiliary system that is driven by an internal combustion engine and an electric motor and provided in a hybrid vehicle or an idling-stop vehicle. The control device is, in particular, suitable for controlling an engine or a transmission mounted in the hybrid vehicle.
Recently, from the viewpoint of saving fuel cost, a hybrid vehicle or an idling-stop vehicle is brought to market. These vehicles stop their engines according to driving condition. Auxiliary units, such as a compressor provided in a refrigerating cycling device, which are driven by the engine, thereby require another drive. As a solution to this, for instance, JP-A-2000-130323 proposes a hybrid-driven auxiliary unit such as a hybrid-driven compressor, to which an electric motor is added as another drive.
Incidentally, operation of an auxiliary unit is controlled by directly detecting its load torque during the operation. This enables response or stability of operational characteristic to be enhanced, so that desired torque or output of the engine can be easily obtained. This results in eliminating waste of consumption energy of the engine.
One of technologies for directly detecting the load torque is described in JP-A-2001-132634. The technology is directed to a compressor. Here, a load torque detector disposed in a pulley detects, as the load torque, pulley""s mechanical distortion derived from torsion of a driving shaft.
However, the above technology involves providing of the dedicated load torque detector, so that cost is increased.
It is an object of the present invention to provide a control device that is provided in a hybrid-driven auxiliary system and able to compute a load torque without a dedicated load torque detector.
To achieve the above object, a control device in a hybrid-driven auxiliary system using an engine and a motor for driving force is provided with the following. An auxiliary unit is provided as being operated with the engine or the motor that is integrally assembled into the auxiliary unit. A first or second electric current is controlled and detected, wherein the first is to be supplied to the motor while the motor is used as the driving force. The second is to be generated by the motor while the engine is used as the driving force. A load torque while the auxiliary unit is operated is computed based on the detected electric current.
This structure enables, without dedicatedly providing a load torque detector, the load torque for operating the hybrid-driven auxiliary unit to be computed from the electric current of the motor. The engine can be thereby controlled based on the computed load torque.